1. Field of the Invention
Aspects of the present invention relate to a transport stream (TS) generating device, a transmitting device, a receiving device, a digital broadcast system having the same, and a method thereof. More particularly, aspects of the present invention relate to a transport stream (TS) generating device, a transmitting device, a receiving device, a digital broadcast system having the same, and a method thereof, in which power consumption of the receiving device of an ATSC VSB system is reduced, and multi TS including turbo stream and normal stream of various coding rates is transmitted and received.
2. Description of the Related Art
An ATSC VSB digital broadcast system adopts a field sync signal in the unit of 312 segments. Therefore, reception degrades in the poor channel such as a Doppler fading channel.
FIG. 1 is a block diagram of a conventional ATSC DTV transmitter and receiver. The ATSC VSB system uses a dual transport stream (TS) which includes normal data and turbo data added to normal data.
Referring to FIG. 1, a digital broadcast transmitter performs error correction encoding of dual TS. Accordingly, the digital broadcast transmitter includes a randomizer 11 to randomize a dual TS, a Reed-Solomon (RS) encoder 12 of concatenated coder type to correct an error generated during the transmission process due to a channel characteristic, an interleaver 13 to interleave RS-encoded data, and a trellis encoder 14 to map, by trellis encoding at the rate of ⅔, the interleaved data into 8-level symbol.
A digital broadcast receiver includes a multiplexer 15 to insert field sync and segment sync into error-corrected data to form the data format illustrated in FIG. 2, and a modulator 16 to add a DC value to a data symbol which has the field sync and segment sync inserted therein, insert a pilot tone, perform pulse-shape and VSB modulation, convert the signal into a signal in RF channel band, and send out the signal.
Accordingly, a digital broadcast transmitter and receiver adopting a dual TS scheme multiplexes normal data and turbo data and inputs the multiplexed data to the randomizer 11.
The input data is randomized at the randomizer 11, and the randomized data is outer-coded at the RS encoder 12 employed as an outer coder. The coded data is rearranged at the interleaver 13.
The interleaved data is inner-coded at the Trellis encoder 14 based on the 12 symbol units, and the inner-coded data is mapped to 8-level symbols. Field sync and segment sync are inserted, and then pilot tones are inserted. The data is converted into RF signal by VSB modulation and forwarded.
Referring to FIG. 1, the digital broadcast receiver includes a tuner (not shown) to convert the RF signal received through a channel into a baseband signal, a demodulator 21 to perform synchronization detection and demodulation of the converted baseband signal, an equalizer 22 to compensate for multipath channel distortion of the demodulated signal, a viterbi decoder 23 to correct the error of the equalized signal and decode into symbol data, a deinterleaver 24 to rearrange the interleaved data from the interleaver 13 of the digital broadcast transmitter, a RS decoder 25 to correct the error, and a derandomizer 26 to derandomize the corrected data from the RS decoder 25 and to output MPEG-2 transport stream.
As explained above, the digital broadcast receiver of FIG. 1 down-converts the RF signal into baseband, by the processing performed in reverse order to that at the digital broadcast transmitter. The digital broadcast receiver then demodulates and equalizes the converted signal, and performs channel decoding to recover the original signal.
FIG. 2 illustrates a VSB data frame of a U.S-oriented digital broadcast (8-VSB) system in which segment sync and field sync are inserted. As illustrated, one frame includes two fields, and one field includes one field sync segment in the first segment, and 312 data segments. One segment of a VSB data frame corresponds to one MPEG-2 packet, and one segment includes four symbol segment sync and 828 data symbols.
Referring to FIG. 2, segment sync and field sync are used at a digital broadcast receiver for synchronization and equalization. Field sync and segment sync are data previously known to a digital broadcast transmitter and a digital broadcast receiver, and used as a reference signal during equalization by the digital broadcast receiver.
Variable coding rates may be applied to turbo data depending on broadcast programs, and the turbo data may be included in dual TS. Accordingly, dual TS may be generated, including normal data and turbo data of various coding rates.
However, a conventional digital broadcast system does not provide transmission and reception of dual TS including normal data and turbo data of various coding rates.
Accordingly, a digital broadcast system is required, which is capable of processing transmission and reception of dual TS including normal data and turbo data of various coding rates.